Zoom Lens Flare Cutting Stop Arrangement
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Solution Overview
Problem
Existing zoom lenses with high magnification and wide angles face challenges in downsizing, reducing weight, and achieving high optical performance due to increased effective diameters of lens units, which complicates the mechanism and affects operability and image field changes, especially around the F-drop point.
Innovation Solution
A zoom lens configuration with specific conditional expressions for focal lengths and distances of lens units, including a first lens unit with positive refractive power, one or two second lens units with negative refractive power, a stop for off-axis light reduction, two or three third lens units with positive refractive power for zooming, and a fourth lens unit, optimizing the arrangement of the flare cutting stop to effectively cut off-axis light without affecting the f-number.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the effective diameter of the third lens unit is increased to achieve high magnification and wide angle with small f-number, then optical performance is improved, but the mechanism becomes more complex and the weight increases
Solution Approach 1:
The patent extracts the function of cutting off-axis light from the third lens unit by introducing a dedicated flare cutting stop. This stop is positioned between the second and third lens units and is responsible for cutting off-axis light that would otherwise require a larger third lens unit. By separating this function, the third lens unit can maintain a smaller effective diameter while still achieving the desired optical performance for high magnification and wide angle with small f-number.
2Reliability
If the effective diameter of the third lens unit is increased to achieve high magnification and wide angle with small f-number, then optical performance is improved, but the weight increases
Solution Approach 1:
The patent extracts the function of cutting off-axis light from the third lens unit by introducing a dedicated flare cutting stop. This stop is positioned between the second and third lens units and is responsible for cutting off-axis light that would otherwise require a larger third lens unit. By separating this function, the third lens unit can maintain a smaller effective diameter and thus reduced weight while still achieving the desired optical performance for high magnification and wide angle with small f-number.
3Reliability
If the flare cutting stop structure is extended from the third lens unit toward the second lens unit, then off-axis light cutting is improved, but the mechanism becomes more complex
Solution Approach 1:
The patent introduces an intermediary flare cutting stop positioned between the second and third lens units. This stop acts as a mediator that handles the off-axis light cutting function independently, rather than extending the third lens unit structure toward the second lens unit. The flare cutting stop is positioned at an intermediate location where it can effectively cut off-axis light without requiring structural modifications to either the second or third lens units, thus maintaining mechanism simplicity.
4Reliability
If the flare cutting stop moves inverted discontinuously after the F-drop point, then off-axis light cutting is maintained, but operability and image field change rate are affected
Solution Approach 1:
The patent applies dynamics by making the flare cutting stop movable rather than fixed. The stop moves along the optical axis in coordination with the zooming operation, with its position dynamically adjusted based on the focal length. The movement follows a continuous trajectory defined by conditional expressions relating the stop position to the focal length, ensuring smooth operation without inverted discontinuous movements. This dynamic positioning maintains effective off-axis light cutting throughout the zoom range while preserving operability and image field change rate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables a zoom lens with improved optical performance, downsizing, and reduced weight by effectively cutting off-axis light flare, maintaining high magnification and wide angle capabilities while simplifying the mechanism and enhancing operability.
Implementation Method 1
a stop configured to reduce an outer part of an off-axis light
Implementation Method 2
a first lens unit having a positive refractive power, which is configured not to be moved for zooming; one or two second lens units having a negative refractive power and configured to be moved for zooming
Data Source
AI summary
Provided is a zoom lens including, in order from object side: a positive first unit configured not to be moved for zooming; one or two negative second units configured to be moved for zooming; a stop configured to reduce an outer part of an off-axis light; two or three third units configured to be moved for zooming; and a fourth unit, in which focal lengths of the first unit and the second units, a distance on an optical axis from the stop to a vertex of a surface closest to the object side in the third units under a zoom state in which F-drop starts, and a distance on the optical axis from a vertex of a surface closest to the image side in the second units to the vertex of the surface closest to the object side in the third units under the zoom state are appropriately set.